There was a bug in Angular where we had a signature
static forEachWithIndex<T>(array: T[], fn: (T, number) => void) {}
which I'm fixing:
angular/angular@7de9979
because of course without --noImplicitAny it's the same as
static forEachWithIndex<T>(array: T[], fn: (T: any, number: any) => void) {}
which looks completely silly. And the callback may have a large body with many dereferences from these parameters which no one realizes are unchecked.

This is very unfortunate of course, but I think we could statically detect cases where the name of an untyped parameter in a position like this collides with a type expression, and warn/error to save the user from this.

It's not an isolated case, I'm sure. In fact for Java, I started the error-prone project (http://errorprone.info) which augments the Java compiler with third-party type checks, including mis-usages of common libraries. @eaftan and @cushon did most of the work and made that very successful, running it in every Java compilation at Google and promoting most checks to compile errors (of course using criteria for making these into type errors, which we document http://errorprone.info/docs/criteria)

I wonder what the TypeScript team thinks about further static analysis beyond the TypeScript spec. Do you think it's valuable to extend the compiler with a third-party plugin that catches classes of errors outside the language spec?